Su Doku, the Japanese numbers game, may have gripped Britain, but there is surprisingly little interest among pupils in its homeland.
So when a Japanese news crew read in The TES how the craze is sweeping British schools, they flew 6,000 miles to film children at Oulton Broad primary filling in a grid in their playground.
Chris Harrison, head of the Suffolk school, challenges his junior pupils to complete the puzzles in just 15 minutes. Now he is keen for his pupils to take part in The Times National Su Doku championships, which kick off with qualifying puzzles next week.
The Japanese news crew spent a morning at Mr Harrison's 200-pupil school.
"They read about us in The TES and were fascinated that children in the UK are interested and able to solve Su Doku problems, because they are not something of interest to children in Japan," he said.
Su Doku is a logic puzzle in which the numbers one to nine have to be fitted into a nine by nine grid in such a way that each number appears once only in each column, row and three by three box.
Schools are using the game as a mental maths warm-up, an introduction to logic or simply an end-of-lesson time-filler.
The Times competition features three categories. A qualifying puzzle for primary children will be published in the paper on July 6 and one for secondary pupils will appear on July 7.
Adults will get six cracks at qualifying with a fiendish puzzle printed each day from Monday, July 4.
The 50 fastest primary and 50 fastest secondary pupils will be picked for the finals at Cheltenham Ladies College on October 16. There will be 300 adult finalists.